New occurrences, mean infestation intensity and prevalence of parasitic isopods (Isopoda, Cymothoida, Bopyridae) associated with Macrobrachium amazonicum (Decapoda, Palaemonidae) from the mouth of the Amazon River.

The Amazon prawn or Macrobrachium amazonicum (Heller, 1862) is widely distributed in South America, occurring in the Orinoco and Amazon rivers, and forms an important source of income for riverside families. This prawn hosts crustacean ectoparasites of the genus Probopyrus (Giard & Bonnier, 1888) (Bopyridae) that infest its gill cavity. The aim of the present study was to report new occurrences of Probopyrus in Amazon prawns caught in the Amazon River. Macrobrachium amazonicum prawns were collected between May 2017 and April 2018, and again from July 2021 to May 2022 in the regions of Ilha de Santana and Rio Mazagão, state of Amapá, Brazil. Among the 5,179 prawn specimens caught, 133 were parasitized by the ectoparasites Probopyrus pandalicola (Packard, 1879), Probopyrus bithynis (Richardson, 1904), Probopyrus floridensis (Richardson, 1904) and Probopyrus palaemoni (Lemos de Castro & Brasil Lima, 1974). These occurrences of P. floridensis and P. palaemoni in M. amazonicum were the first records of this on the northern coast of Brazil. These four ectoparasites are not limited to specific host species or genera, as observed in this study, which reports four species of Probopyrus infesting M. amazonicum.